This invention relates, generally, to the manufacture of thin films and, more particularly, to a semi-automatic apparatus for diverting a continuously advancing, broken film to waste.
In existing machines, film is manufactured by extruding a web of molten, polymeric, film-forming materials onto a quench wheel and then advancing the web through stretching and slitting stations to one or more windups. Equipment for cutting and diverting the stretched film in the event of a discontinuity between its beads or edges has been disclosed by Huskey in U.S. Pat. No. 3,762,250. The film is diverted to a waste shredder until the discontinuity has been healed. Even though the equipment is normally effective, there are still situations in which a discontinuity can cause entanglements. Such entanglements, in turn, cause broken beads or wrapping of the film on transfer rolls, in which events there is a stoppage of film to the waste shredder and an accumulation at the exit of the stretching station. Stretched film also accumulates if, for any reason, the waste shredder system is inoperable. Whenever continuity is lost to the waste shredder, the casting line speed is reduced to facilitate manual handling of the accumulated waste. Speed can be reduced rapidly or below a certain level only at the risk of a burn-through in the stretching station. At the same time, if speed is not reduced sufficiently, difficulties are encountered by the operators who must handle the accumulated waste. But for the need to reduce speed for stoppages due to breaks and entanglements, the throughput of all existing machines could be increased appreciably.